Volcanic islands can form over hot spots. The Hawaiian Islands started forming over hot spots in the Pacific Ocean millions of years ago. What process causes the hot, solid rock to rise through the mantle at these locations?

Convection Currents

Explanation:

Due to the different   temperature occurring at the  upper and lower layers  of the mantle, it causes  heat transfer to occur. One of such heat transfer is the Convection currents which causes  warmer, less dense rock material in the core to rise through the mantle. Also, the cooler rocks in the higher mantle move slowly towards the core.The movement caused by these  Convection current in the Earth are  called plate tectonics which are responsible for earthquakes and volcanoes.